Carts having a frame and a basket used in supermarkets are commonplace. Ideally, carts of this type should have the following characteristics. First, they should be able to withstand a great deal of abuse, particularly to the basket portion. Carts are continuously impacted with each other and with stationary objects. Second, the carts should be easy to push and to maneuver. The condition of the wheels has a great effect on this characteristic as does the weight of the cart. Third, the carts should be of such design and surface finish to avoid a propensity to collect dirt and contaminants. Fourth, the carts should be able to withstand cleaning by strong detergents or steam. Fifth, the carts usually must have sides of open lattice construction, because customers wish to be able to observe the contents of the carts from any angle. Sixth, the carts should be attractive and should maintain their attractiveness over a long period of time.
Carts with metal baskets do not satisfy all of these requirements. The wires in the baskets are welded at the crossing points, and the basket is chrome-plated to provide a smooth, cleanable, attractive surface. Because the welding and plating process is intricate, it is common to have welds and plating of marginal quality so that, upon hard impact or upon a series of impacts over a period of time, the welds and plating are broken. The plating is also subject to being removed by wear and scraping against other objects. This allows the base metal to rust. Also, if the basket is used in an environment where corrosion of metals is a problem, such as in grocery stores, the base metal exposed at the broken plating and broken welds will corrode. The cart, and particularly the basket, then becomes unsightly and unattractive. At these exposed points, food particles can become entrapped in small cracks and crevices despite periodic cleaning, yielding unsanitary carts. In addition, articles placed in the basket can become pinched or snared by the unsecured wires and plating, in conveniencing the customer and damaging the goods. Impacts also frequently inwardly deform the basket, giving rise to all of the above problems.
Repair of metal cart baskets is a problem because it is difficult to bend the wires back into shape, and it is difficult and expensive to reweld and replate the wires. The cart frame and the basket are often integral with each other and therefore cannot easily be taken apart for repair or replacement of components. To replace the basket, welds must be broken, then replaced. Complicated bending and interlocking of wires frequently is necessary during disassembly and assembly. Usually, the cart is simply not repaired. When it becomes too unsightly or too unsanitary to use it is discarded. The loss of the entire cart for the sake of the basket is uneconomical. Metal carts are also quite heavy, making them difficult to push and to maneuver, especially if they have some malfunction of the wheels.
Carts having plastic baskets have been used to overcome many of the disadvantages of metal basket carts. Such a cart is disclosed in my U.S. Pat. No. 3,999,774 entitled "Cart With Plastic Basket." In such carts the frame is preferably made of chrome plated steel construction and the the cart basket is made of plastic, such as polyethylene. This basket is strong, light-weight, has a smooth finish, and can deform to absorb impact and then return to its original shape. The sides, front and bottom of the plastic basket are integrally molded in one piece. There are no seams to break, or cracks and crevices to collect dirt. The plastic does not rust or corrode under the influence of food acids and other chemicals. The use of a plastic basket reduces the weight of an average cart by at least fifteen pounds.
The plastic basket is formed almost entirely of open lattice construction, which further lightens it, and which allows the basket contents to be viewed from any angle. Rigidity is provided to the basket by suitable integral strengthening ribs, and also by the interrelationship between the basket and the metal cart frame, and other components.
It is very important to have a strong basket that will withstand impact and high loading. Therefore, the basket must be provided with reinforcement. Some reinforcement is provided by way of the construction of the basket itself. But the weight of the basket is kept to a minimum, and its strength maximized, by novel relationships between the metal cart frame and the basket which use the metal cart frame as a reinforcing member for the basket. Not only does this provide added strength to the plastic basket, but it allows the basket to be made of materials that would otherwise not be suitable.
In the '774 patent, a metal ring is disposed within a channel extending around the top opening of the upper edges of the basket. The metal ring is provided with a plurality of integral upstanding tabs which are received in complementary openings in the top wall of the channel. The tab and slot arrangement secures the ring within the channel. Similar reinforcing rings may be used with over-the-counter carts (see my U.S. Pat. No. 4,273,346) and with scanner carts (see my U.S. Pat. No. 4,650,199).
Plastic crates, such as plastic milk crates, are also well known in their field. Plastic crates replace wooden and paper crates for transporting, storing and displaying food such as milk cartons. These crates are rectangular and include four side walls and a bottom. The side walls are commonly formed of an open lattice configuration to permit viewing the contents of the crate. The bottom is also formed of an open lattice configuration to prevent accumulation of debris. Various reinforcing structures such as integrally molded ribs are used to strengthen the crates. It is also known, as disclosed in my U.S. Pat. No. 3,390,808, to dispose a metal reinforcing ring within a channel disposed along the top opening of the crate. As with reinforcing rings for shopping carts, the metal ring is provided with upstanding tabs or lugs which project into flanges in the plastic crate to secure the metal ring in position.
However, in both carts and crates, the tab and slot method of securing the reinforcing ring in the top channel suffers numerous disadvantages. Tabs must be formed on the reinforcing ring. A cross-sectionally round ring must be used for the cart basket gate to swing and to complete the back side of the ring. The ring must be formed with dies.